Q5. Why are the cotyledons of a gram seed thick and fleshy?
They are full of reserve food materials (NCERT page 66).
Q6. Assertion: a pea seed is non-endospermic. Reason: pea is a dicotyledon. Are both true, and does the reason explain the assertion?
Both are true, but the reason does not explain the assertion: castor is also a dicotyledon, yet its seed is endospermic (NCERT page 66). A pea seed is non-endospermic because its developing embryo uses up the endosperm completely before the seed matures (NCERT Class 12 Biology, pages 19–20).
Q7. What is the nature of the seed coat in maize?
Membranous, and generally fused with the fruit wall (NCERT pages 66–67).
Q8. In a maize grain cut lengthwise, which part lies between the endosperm and the embryonal axis?
The scutellum, the single large, shield-shaped cotyledon (NCERT Figure 5.15, page 67).
Q9. According to NCERT Class 12 Biology, what does the micropyle do, and what happens to a seed’s water content as it matures?
The micropyle lets oxygen and water into the seed during germination; as the seed matures, its water content falls to 10–15 per cent moisture by mass and the embryo’s metabolism slows down (NCERT Class 12 Biology, page 20).
Q10. Which of these is non-endospermic: castor, maize, orchid, wheat?
Orchid (NCERT page 66); castor, maize and wheat seeds keep their endosperm (NCERT Class 12 Biology, page 20).